Trigeminal autonomic cephalalgias other than cluster headache.

Trigeminal autonomic cephalalgias are short-lasting primary headache disorders associated with autonomic symptoms. Paroxysmal hemicrania is a rare headache disorder similar to cluster headache. Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA) are unusual headache syndromes typified by a high frequency of severe, brief, unilateral attacks that usually occur in the distribution of the trigeminal nerve. SUNCT is a subtype of SUNA in which both conjunctival injection and tearing are present. SUNA differs from SUNCT in that autonomic symptoms are less prominent.